Abstract:

Guanshan River Basin is a major contributory source to the Danjiangkou reservoir and a critical component of the water source area of the South-to-North Water Diversion Project. The composition and spatial distribution of hydrogen and oxygen stable isotopes in Guanshan River Basin were comprehensively examined. The seasonal recharge sources of river water and the factors influencing hydrogen and oxygen stable isotopes were also investigated. Results reveal that δD and δ¹⁸O are higher during flood season than in dry season, with average d-excess values of 12.59‰ and 11.30‰, respectively, for flood and dry season river water. The slope and intercept of the river water line equation in the Guanshan River Basin closely resemble those of the atmospheric precipitation line in the Yangtze River Basin, suggesting that river water is mainly recharged from atmospheric precipitation in the Yangtze River Basin. The isotopic composition during the flood season exhibits a positive signal, primarily influenced by both precipitation and water-rock interaction. The composition of hydrogen and oxygen stable isotopes of river water within the basin is influenced by multiple factors, with evaporation along the river course and elevation effects being the most significant. These research findings are of substantial significance for understanding the regional hydrological cycle within the Guanshan River Basin.

Key words: composition of hydrogen and oxygen isotopes, recharge source, influencing factors, Guanshan River Basin, South-to-North Water Diversion Middle Route Project, hydrological cycle